Aspects of the invention are directed to handheld electronic devices and, more particularly, to handheld electronic devices including double pre-loaded deflection webs for integrated keypad modules.
Numerous types of handheld electronic devices are presently in use. Exemplary handheld electronic devices include personal data assistants (PDAs), handheld computers, two-way pagers and cellular telephones. Many feature wireless communication capability and/or are stand-alone devices that are functional without communication with other devices.
Handheld electronic devices are generally intended to be portable, with many being small enough to fit within a pocket, a belt holster, a briefcase or a purse. As the form factor of such devices has shrunk for improved portability, so has the size of components such as keyboards or keypads. The keyboards or keypads include keys that act as switches for input entry when actuated. In order to further the miniaturization of these components, one general approach has involved the use of an electrical key in the form of a resilient dome-shaped element that is electrically conductive and is disposed on a circuit board.
In simplest form, such a dome element is a smooth sector of a hollow sphere. When an actuation force is applied to the apex of the dome element, the dome element collapses to thereby complete an electrical circuit. The collapsing dome element provides a tactile feedback to the user of the handheld electronic device. Such simple sphere segments have been generally effective for their intended purpose but often the tactile feedback is not noticeable.
Thus, the dome elements are often provided with elastomeric or compliant layers that provide for an improved tactile feel or increase the tactile feel of the dome element. However, due to the small size of the various components, it has been difficult to produce the elastomeric or compliant layers such that they fit with the keys and the other structural elements of the keyboards or keypads. This leads to elastomeric or compliant layers that are too small, which leads to moisture ingress that can damage the underlying components.